1. Technical Field
The present invention relates to unions for coupling a water line to the inlet of a pump, such as that used in hydrotherapeutic spas.
2. Description of the Related Art
Hydrotherapeutic spas or baths include water jets for imparting turbulence in the water. The jets are downstream from one or more water pumps. Each pump is fed water through an inlet flange to which is connected a supply pipe, typically made of polyvinyl chloride material. Conventional supply pipes are of a diameter slightly smaller than the opening to the input flange. Thus, a special union or coupler is used to mate the pipe to the input flange. This coupler can be formed as a part of the flange or can be a separate piece connected in some manner to the flange.
For example, the input flange may have a tubular extension defining the inlet opening. A separate tubular coupler can be mated with the tubular extension by a collar threaded onto the extension and capturing a peripheral flange on the coupler. The wall thickness of the coupler reduces its inner diameter so that it is sized just large enough to accept the outer diameter of the supply pipe, thereby providing the union of the supply pipe to the input flange. One or more o-rings can be used to seal the connection when the collar is tightened. U.S. Pat. No. 5,701,388, hereby incorporated by reference as though fully set forth herein, discloses a similar arrangement and a pump unit of the type for which the present invention is designed to be used.
The problem with the existing constructions is that the wall thickness of the coupler and/or the supply pipe extends radially inward (of lesser diameter) than the opening in the input flange. The coupler and possibly the supply pipe can thus become an obstruction to the return flow of water from the input flange causing damming or pooling of water during periods when the pump is not being operated. The amount of residual water retained in the pump or its supply lines is regulated to reduce the occurrence of bacteria developing in stagnate water. One way of reducing the amount of residual water retention is to raise the pump slightly and tilt it back several degrees from horizontal so that more of the water will drain back through the supply line by gravity. However, doing this can make stabilizing the pump difficult as well as create some downstream water drainage problems in the suction line because of the now decreased overall pitch from the water jets to the pump.
Accordingly, an improved connection at the inlet flange of the pump is desired.